#include<iostream>
#include<cstring>
using namespace std;
const int maxn = 16;
int f[maxn][maxn],n,m,x,y;
bool a[maxn][maxn];

int main(){
	cin>>n>>m>>x>>y;
	a[x][y]=true;
	a[x-1][y-2]=a[x-2][y-1]=a[x+1][y+2]=a[x+2][y+1]=a[x-1][y+2]=a[x-2][y+1]=a[x+1][y-2]=a[x+2][y-1]=true;
	
	for(int i=0;i<=n;i++){
		for(int j=0;j<=m;j++){
			f[0][0]=1;
			if(a[i][j]){
				continue;
			}else if(a[i-1][j] || i-1<0){ 
				f[i][j]=f[i][j-1];
			}else if(a[i][j-1] || j-1<0){
				f[i][j]=f[i-1][j];
			}else{
				f[i][j]=f[i-1][j]+f[i][j-1];
			}
		}
	}
	
	cout<<f[n][m]<<endl;
	return 0;
}